什么时候应该覆盖Equals功能？ [英] when should I override Equals function?

问题描述

<强>可能重复：结果，
Java：总是覆盖等于？

我应该覆盖 equals 我创建的任何类的函数？

should I override equals function for any class that I create?

即使是非常简单的类，只包含一些非常简单的属性，而等于我需要它的每一个属性都相等？

even for very simple classes which only contains some very simple attributes and by equals I need every single attribute of it to be equal?

推荐答案

我应该为我创建的任何类重写equals函数吗？

should I override equals function for any class that I create?

覆盖等于 if（且仅限于）对象代表一些数据，即如果它模拟诸如 Person ， Car 或 RecipieIngredient （这些通常最终出现在集合中等）。不要为其他类型的类重写equals，例如 LoginServlet 或 DatabaseUtil 。

Override equals if (and only if) the object "represents some data", i.e. if it models something such as Person, Car or RecipieIngredient (these typically end up in collections etc). Don't override equals for other types of classes, for example LoginServlet or DatabaseUtil.

每当覆盖等于时，请记住始终覆盖 hashCode 。

Remember to always override hashCode whenever you override equals.

（一个自然的后续问题:) 如果我不重写equals和hashCode会怎样？

(A natural follow-up question:) What happens if I don't override equals and hashCode?

任何两个对象都将被视为不等，除非它们是完全相同的对象。

Any two objects will be considered unequal unless they are the exact same object.

[...]我需要它的每个属性都相等吗？

[...] I need every single attribute of it to be equal?

通常是。这取决于你如何定义你的平等概念。请注意，对于引用类型，您可以重用/委托 对象实现等于（和 hashCode ）实施自己的。

Typically yes. It depends on how you define your notion of equality. Note that for reference types, you can reuse/delegate to that objects implementation of equals (and hashCode) when implementing your own.

相关问题：

'LI> 为什么我们需要在java中重写equals和hashcode以及为什么我们不能使用Object类实现

• 为什么我需要覆盖Java中的equals和hashCode方法？

• why we need to override equals and hashcode in java and why cannot we use Object class implementation
• Why do I need to override the equals and hashCode methods in Java?

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